Semiconductor devices are used in a variety of electronic applications, such as personal computers, cell phones, digital cameras, and other electronic equipment, as examples. Generally, a typical semiconductor device includes a substrate having active devices such as transistors and capacitors. These active devices are initially isolated from each other, and interconnect structures are subsequently formed over the active devices to create functional circuits. Generally these interconnect structures include conductive features (e.g., metal lines and vias) formed in a plurality of stacked dielectric layers.
Typically, different metal lines in a dielectric layer are formed of a same material, such as, copper. The use of copper may allow for improved electrical characteristics (e.g., improved electro-migration (EM) characteristics). However, as the dimensions of various features in semiconductor devices (including metal lines) shrink in advanced node devices, the continued use of copper for fine line-width applications may create complications in process formation and reduce device performance. For example, resistance of copper lines may increase to an undesirable level as line width decreases, voids may result from fine line-width formation processes using typical copper damascene processes, and the like.